Treatment of hydrocarbon oils



Oct. 30, 1934. 4v. MKLER 'y 1,978,592 TREATMENT OF HYDROCAHBON OILS I AFiled Feb. 5, 1952 3 Sheets-Sheet 1 I IVENTCR VALENTINE MEKLER Oct. 30,1934. v. MEKLER TREATMENT OF HYDROCARBON OILS 5 Sheets-Sheet Y2 FiledFeb FIG 2 INVENTOR VALENTINE MEKLER Filed Feb. 3, 19.32 3 Sheets-Sheet 3FIG. 3 v

INVENTOR VALENTINE MEKER ATTORN refining of the product.`

Patented Oct. 30, i934 UNITED STATES PATENT OFFICE mlm 0l' maoonnoa onsalentinelekleaCldMm-.aldgnortolld- Company jversaloilrroinctscerponticnelsonthllakoh mamma-fiamminga. msu' z om or rae-m In one ofits specific embodiments the invention comprises subjecting hydrocarbonoils to crack-v ing or conversion conditions of temperature by directadmixture therewith of hot combustion gases and subsequent furtherheating of the mixture by indirect contact with the hot combustiongases, whichin turn are cooled prior to admixture with the hydrocarbonsto be cracked. Thus,V approximately l0 to 90 percent of the total heatrequired is applied by indirect means. The necessary time for the vaporsat the cracking temperatlure to cause the desired conversion is allowedand thereafter the vapors are fractionated and condensed, collecting thelow boiling product of the process and subjecting the reflux condensatefrom the fractionating zone to further cracking if desired. The gasesmay be treated in the usualmanner for recovery of absorbed condensablelow boiling hydrocarbons contained therein. Ordi- `narily in directheating processes the vgases of combustion must'becooled by admixingtherewitha gaseous cooling agent prior to admixture' with thehydrocarbon vapors, thus producing an abnormally high content ofincondensable gases. 'I'he present process overcomes this objectionablefeature.

It will be obvious from the following description that the presentprocess possesses all of the advantages of the high temperature crackingprocesses wherein the hydrocarbons are heated by indirect means, such ashigh anti-knock product, but does not have the disadvantages of .highgas losses and a product containing high gums; on the other hand, itpossesses all of the advantages of processes wherein hydrocarbons arecracked by direct contact with hot combustion 'gases but 'does not havethe disadvantages of diluting the "hydrocarbons with excessive amountsof combustion gases which causes an increase in initial investment forlarger equipment and larger operating costs.

Figure 1 of the attached diagrammatic drawings illustrates. in crosssectional elevation, a

` portion of a vapor-phase oil conversion process to which theprinciples of the present invention have been applied. .Combustionchamber 1 is ilred through one or a plurality of firing timnels 2 towhich fuel, in the form of oil, gas or pulverized solid fuel may besupplied through line 3 and valve 4 and introduced into the ring tunnelthrough 'a suitable burner, Vnot shown, and enclosedwithinthe end5oftheilringtunnel. Air,

steam or other atomizing and combusticnsup- Y porting medium may besupplied tothe burner through line 6, valve 1, line 8 and valve 9. '111ecombustion chamber 1 ispreferably a steel chamber, capable ofwithstanding super-atmospheric pressures, lined with suitable refractorymaterial indicated at 12. The combustion products may' pass fromcombustion chamber 1 through duct 13 to mixing chamber 14.

'Mixing chamber 14 preferably comprises outer casing -of steel, capableof withstanding super-atmospheric pressures, lined with suitablerefractory material 12 and having concentric baille walls 15 and 16 ofany suitable material such as. for example, refractory shapes orhightemperature metallic alloys; for example, silicon carbide. Aninverted mixing cone 11 may be located within baille 16, as illustratedin the drawings, hydrocarbon vapors being supplied to this zone throughline 18 and valve 19. 'Ihe com bustion gases from combustion chamber 1pass first' downward in mixing zone 14 around baille 15, thence passingupward within baille 16 and coming into direct contact and comminglingwith the hydrocarbon vapors by means of a multiplicity of perforations20 in mixing zone 17, serving to heat said hydrocarbon vapors by contactand direct admixture therewith. 'Ihmmixture of hy' drocarbon vapors andcombustion gases may pass upward through the inner portion 21 of mixingzone 14, thence pass downward between baffles 15 and 16, being heatedduring their e through this zone by indirect contact with the combustiongases prior to the admixture of said combustion gases with thehydrocarbon vapors and by radiation from the hot walls of the mixingchamber. 4The hydrocarbon vapors are thus heated-to the desiredconversionv temperature, ilrst by direct mixing with the partiallycooled combustion gases and second, together with said admixedcombustion gases which also serve to dilute the hydrocarbon vapors, byindirect contact with the relatively hotcombustion gases and heatingfrom radiating walls of the mixing chammospheric pressures and, likezones l and 14, may

be lined with suitable refractory material V11|. The vapor-gas mixturemay enter reaction chamber- 23 at its lower portion passing upwardaround the inner zone 24, the walls 2s of which serve as a bailledirecting the materials undergoing conversion iirst upward around theirouter circumference and then downward through zone 24 and out of thereaction chamber through duct 26.

Further treatment of the hydrocarbon combustion gas mixture such asfractionation, scrubbing, separation and final collection of thedesirable products may be effected in Well known forms of apparatus, notillustrated in the drawing, and not a specic part of the presentinvention.

Uncondensable hydrocarbon gases, together with combustion gases from theprocess and/or steam, or any inert gases, or combination of the above,may be recycled by a pump or compressor, not shown, through line 27 andvalve 28 and may be supplied through line 29 and valve 30 into duct 13and/or through line 31 and valve 32 into the outerl portion of mixingchamber 14, serving as a means of diluting and increasing the volume ofthe combustion gases, reducing their temperature to the desired degreebefore they are admixed with the hydrocarbon vapors. If desired, air orother combustion supporting medium may be diverted from line 8 throughline 19 and valve 11 into line 29 to mix with said recirculated gasesand eiect combustion of hydrocarbon gases therein when introduced intothe relatively hot mixing zone 14 or duct 13.

A preferred form of apparatus which combines the combustion and mixingzones in a single structure is illustrated diagrammatically in Figures 2and 3 of the attached drawings. Figure 2 is a cross-section' elevationof the apparatus and Figure 3 is a plan view of the same apparatus alsoshown partially in a section taken along line 3--3 in Figure 2.Referring now to Figures 2 and 3, the entire furnace is preferablyencased in a steel shell 91 in order to permit the use ofsuper-atmospheric pressures in the operation of the process, if sodesired. This shell may be anged at 92 and joined thereby with the upperhead 93 of the heating and mixing unit which may comprise an uppermixing head 94 and lower header 95 and one or more concentric rows oftubes 96 which may be welded, rolled or otherwise joined at their upperends to mixing head 94. and at theirlower ends to header 95. Mixingheader 94 may comprise concentric outer and inner walls 97 and 98respectively, resembling an' inverted U, when shown in cross-section, asin Figure 2, and provided with a multiplicity of perforations 99 throughwhich the combustion gases may pass to mix with the hydrocarbon vaporsin header 94. l

The lower header 95, wherein the heated hydrocarbon vapors and admixedcombustion gases collected after passage through the tubes 96, may bereleasably joined, for example, by means of a slip joint arrangement, asindicated at 110, to the outlet line 111. It will be evident that byproviding any desired form of joint of this general type, the entireheating and mixing unit may be removed from the furnace for cleaning orrepairs simply by unbolting the flange joint 92 and lifting the heatingand mixing unit from the fur- This arrangement provides for expansion ofthe assembly upon heating. It willv be understood that well known means,not illustrated, may be provided, if desired, for obtaining access toheaders 94 and 95 and to tubes 96 without removing the unit from thefurnace.

The walls 112 of the furnace may be constructed of any desiredrefractory material.

A central bale 113, preferably of any suitable high temperature metallicalloy, may be joined to or formed integral with header 95 extendingupward from this header to a point relatively close to upper mixing head94 and within the concentric row of tubes 96. An outer balile 114 of thesame or similar temperature resistant material, as baille 113, may beprovided outside the concentric rows of tubes 96 and may, if desired, beattached tothe walls 112 of the furnace. If spaceis left between bale114 and walls 112, as illustrated in the drawings, vents 115 arepreferably provided to allow for expansion of the gases within thisspace. Similarly a vent 116 may be provided in baille 113. Additionalperforations similar to 115 may be provided in baiile 114, the

purpose of which will be more fully described later. l

vThe furnace may be fired with any suitable fuel such as oil, gas orpulverized solidfuel introduced to burners 117 and 117' through lines118 and V118' regulated by valves 119 and 119. Air and/or steam may alsobe supplied to burners 117 and 117 through lines 120 and 120 regulatedby valves 121 and 121'. As in Figure 1, a mixture of hydrocarbon gasesand combustion gas from the process may be recirculated to thecombustion and mixing zone through lines 124 and 124.-' controlled byvalves 125 and 125', in which event the perforations 115, in baie 114,serve as a means of distributing the recirculated gases to thecombustion and mixing zone. l

Steam or any inert gas may also, if desired, be supplied through lines124 and 124', controlled respectively by valves 125 and 125', to theheating zone, serving as a means of diluting and increasing the volumeof the combustion gases, reducing` their temperature to the desireddegree before they are admixed with the hydrocarbon vapors.

Also, as described in connection with Figure l, air or other combustionsupporting medium may, if desired, be mixed with the recirculated gasesfor the purpose of effecting combustion of the hydrocarbon gases in themixture. This material may be supplied, for example, through lines 122and 122 and valves 123 and 123'. It will be understood that, byvariation of the size and location of vperforations 115, therecirculated gases or other medium may be introduced at any desiredpoint or points in the furnace.

The burners 117 and 117' supply the combustible materials to ringtunnels 126 and 126 and the ignited materials preferably enter thecombustion zone 127 of the furnace tangentially in order to impart aturbulent and swirling motion to the combustion gases.

The combustion gases pass from combustion zone 127 upward around thetubes 96 through the restricted area between baiies 113 and 114. Theserelatively hot furnace gases, serving to heat thematerial passingthrough tubes 96, are somewhat cooled thereby and may pass into directcontact and admixture with hydrocarbon vapors introduced to mixingheader 94 through port 128, said combustion gases being admittedpreferably in the form of a multiplicity of finely divided streamsthrough perforations 99 in header 94. The mixture of hydrocarbon vaporsand combustion gases thence passes downward through tubes 96, beingheated in their passage therethrough, by the relatively hot furnacegases, as already described. Heated materials from tubes 96 may becollected` by means of header 95, passing therefrom through dischargeline 111 to subsequent portions of the apparatus, not shown, for furthertreatment.

It will be understood that the apparatus illustrated in the drawings isonly representative of some of the many types of heating equipment inill@ which the principles of the present Invention may be utilized toadvantage and therefore should not be construed as limitations upon theinvention.

In order to compare the operating conditions which may be employed andthe results obtainable from the present improved process, as comparedwith cracking operations u izing other heating means. we will rst considr an operation representative of the conditions prevailingl invapor-phase cracking processes in which direct heating is utilizedexclusively, i. e., all of the heat is supplied to the hydrocarbonvapors to be treated by mixing them directly with hot combustion gases.Assuming a raw oil feed to the system of '100 gallons per hour, a refluxratio of 3, (i. e., 3 gallons oi. reflux condensate recycled to thesystem for retreatment, together with each gallon of raw oil charged)and assuming the weight of the combined feed'l (reflux and raw oil) tobe 'I1/2 pounds per gallon, a total of 3000 pounds per hour of oilvapors are to be treated. Assume that the temperature of the vaporsentering the mixing device is 859 F. and that the conversion temperatureof the hydrocarbon-vapor combustion-gas mixture leaving the heating andmixing chamber is 1000 F. The 'total heat required willl beapproximately 445,000 B. t. u.s per hour. Assuming that the combustiongases are mixed with the hydrocarbon` vapors at a temperature of V1800F. and are cooled thereby to the outlet temperature by 1000 F., abovementioned, the available heat is approximately 265 B. t. u.s per poundof combustion gas and the quantity of combustion gas requiredwill be1680 pounds per hour. Assuming a super-atmospheric operating pressure ofabout 50 pounds per square inch, the total volume of combustion gasesrequired at 1000 F., which is the approximate inlet temperature to thereaction chamber, and at the operating pressure will be approximately13,200 cubic feet per hour while the total volume of oil vapors underthese same conditions will be approximately 3,300 cubic feet p'er hour.The volume of the mixture is therefore 16,500 cubic feet per hour andthe ratio .of combustion gasto hydrocarbon vapor is approximately 4 to1.,

Considering now for the purpose of comparison an operation similar tothe above except that the principles of theV present invention are used;utilizingthe same charging stock, assuming the same reflux ratio and thesame total quantity of -combined-feed (3000fpounds'per hour) the same svapor inlet temperature .(850" F.)` to the heating and mixing device andthe same conversion temperature `(1000 F.), the temperature of the combustion gases mixed with the hydrocarbon vapors may bereduced to about12001400 F., and with the temperature of the furnace gases leaving thecombustion zone at about 3700"V F. the heat available, for both directand. indirect heating, is approximately 900-950 B. t. u.s per pound. Thequantity of combustion gases required is about 400-450 pounds per hourwhich, at 12001400 F. and 50 pounds pressure, will .occupy approximately3200-3500 cubic feet. 'With the quantity of oil vapors remaining thesame (3300 cubic feet) the total volume Aof the mixture under-theoperating conditions-given will be approximately 6700 cubic 'feet perhour and .the ratio of `combustion gasesl to hydrocarbon vapors is onlyslightly greater than 1 to 1. Y

By comparison of the total volume of combustion-gas hydrocarbon-vapormixture in the two examples (16,500 cubic feet per hour by directheating as compared with 6500-6800 cubic feet per hour by a combinationof direct and indirect heating) it will be apparent that the capacity ofa given apparatus may be increased nearly 21/2 times by employing theprinciples of the present invention or, for a given capacity,aproportionately smaller apparatusmay be utilized in the practice of thepresent invention.

An operation such .as rst described utilizing direct heatingexclusively, may yield some 55% of Amotor fuel and approximately 12% offuel oil, giving a total liquid recovery of about 67% based on the rawoil charged to the system, the

remainder being uncondensable gas, coke and semi-solid polymerizationproducts. The gasoline may be of high anti-knock value comparing,possibly, to an octane number of about 80.

The yields obtainable from an operation such as outlined in the secondexample, in which the features of the present invention are utilized,and employing gas oil as a charging stock, may yield 60% or thereaboutsof motor fuel corresponding in antiknockvalue to an octane number ofabout and in addition about 15% of marketable fuel oil may be produced,the remaining products being principally uncondensable gas and arelatively small percentage of carbonaceous' material.

The process is not limited in respect to the charging stock used and aWide range of operating conditions may be employed. Hence the aboveexamples are to be considered as illustrative and not as limitationsupon the broad scope of `the invention.

I claim as my invention:

1. In the vapor phase cracking of high boiling hydrocarbons for theproduction of lower boiling condensible products therefrom, the methodwhich comprises mixing hydrocarbon vapors, free of liquid oil, withpartially cooled combustion gases, dividing the resultant liquid-freemixture int-o a plurality of parallelly flowing streams and passing thesame in indirect heat-exchange with hotter combustion gases whereby thelatter are cooled and the mixture heated, then utilizing thelast-'mentioned gases as said partially cooled combustion gases,controlling the amount and temperature of the heating gases prior tosaid heat exchange to convert a substantial portion of 'the'hydrocarbons into lowerl boiling condensible vapors without completegasification of the hydrocarbons, and condensing and recovering asauproduct of they formed.

2. In the vapor phase cracking of high boiling hydrocarbons for theproduction of lower boiling condensible products therefrom, the methodwhich comprises mixing hydrocarbon vapors, free process thelow boilingvapors thus of liquid oil, with partially, cooled combustiongases,dividing theresultant liquid-free mixture l into a plurality ofparallelly flowing streams and passing the same countercurrent to and inindirect heat exchange with hotter combustion gases whereby the latterare cooled and the mixture heated, then utilizing the last-mentionedgases as said partially cooled combustion-gases, controlling theamountand temperature oi the heatving gases prior to said heat exchangeto convert a substantial portion of the hydrocarbons into .lower boilingcondensible vapors without complete 1 gasification of the hydrocarbons,and condensing and recovering as a product of the process the lowboiling vapors thus formed.

x 'VALENTINE MEKLER.

